Apparatus for forming tamper-proof closures

ABSTRACT

A new tamper-proof closure and apparatus for forming such tamper-proof closures is disclosed herein. The closure includes a cap having a plurality of circumferentially spaced slits separated by bridges with a plurality of lines of weakness extending perpendicular to the slits and aligned with the respective bridges. The lines of weakness have a residual thickness which varies between opposite ends. The apparatus includes a cutting and scoring tool having a first elongated member that defines a cutting edge which has spaced V-shaped recesses and a second member having an elongated surface extending across each of the recesses with the elongated surface having a plurality of projections that extend perpendicular to the cutting edge and are centrally spaced with respect to the V-shaped recesses.

BACKGROUND OF THE INVENTION

The present invention relates to metal closures which are threadedlyreceived on the neck of a container and have a pilfer-proof skirt. Theinvention also relates to apparatus for forming such a closure.

The use of threaded closures to replace the conventional crown hasbecome more and more popular in recent years, particularly in thecarbonated beverage industry. The primary advantage of a threaded metalbottle closure is that the bottle can be resealed after it has initiallybeen opened.

One type of threaded closure that has been used includes what is knownas a pilfer-proof skirt which initially is formed as an integral part ofthe closure and which is separated from the closure when the closure isinitially removed from the bottle. This type of pilfer-proof skirt isformed by producing circumferentially spaced slits around the peripherallower edge of the closure and the slits are separated by small bridgeswhich are ruptured when the closure is removed from the bottle leavingthe pilfer-proof skirt on the bottle. Because of the recent publicinterest in recycling of containers, such a closure has seriousdrawbacks since the pilfer-proof section cannot readily be removed fromthe bottle for recycling purposes.

In order to avoid such objectionable permanently retained section on thebottle, a more recent development in pilfer-proof closures is disclosedin U.S. Pat. No. 3,601,273 wherein the closure again hascircumferentially spaced horizontally extending slits around theperipheral lower edge thereof with vertically extending score lines inthe lower portion of the closure that defines the pilfer-proof ortamper-proof section of the closure. In the closure illustrated in thispatent, the vertical scores are ruptured when the closure is initiallyremoved from the bottle. Because the vertical scores are randomlypositioned on the pilfer-proof sections, some scores may be in alignmentwith the horizontal slits which may produce sharp pointed sections thatproject outwardly when the closure is initially removed from the bottleand results in a hazardous condition for anyone attempting to reuse theclosure. This type of closure is formed by initially stamping a cap froma flat sheet with a press and producing internal vertical scoresextending from the free end of the caps. The cap is transferred to arolling machine which includes a stationary mandrel with a plurality ofspindles that are moved around a circumferential path around theperimeter of the mandrel and are simultaneously rotated about their ownaxes. The spindles support the metal caps which are simultaneouslyknurled and the peripheral circumferentially spaces slits are formedtherein. The closures are then placed on a bottle in another rollingoperation which forms the threads in the closure wall and simultaneouslydeforms the free edge of the closure inwardly below a bead that is onthe neck of the bottle.

Quite recently a new type of pilfer-proof closure has been developed,which is disclosed in Hannon, U.S. Pat. No. 3,861,551 and is similar inmany respects to the previous closure discussed above. The uniquefeature of the closure shown in the Hannon patent is that the verticalscores on the pilfer-proof skirt are accurately positioned with respectto the bridging members between the circumferentially spaced horizontalslits to prevent the formation of sharp pointed sections which projectoutwardly from the skirt.

The disclosure of the Hannon patent also incorporates apparatus forproducing the closures disclosed therein and the apparatus and methodfor forming such a closure are covered by U.S. Pat. No. 3,824,941. Theapparatus disclosed in this patent consists of initially forming anupper knurled band on the cap, subsequently forming a lower outwardlyextending bulge which may also be knurled to produce a second band andsubsequently slitting the outwardly directed bulge and scoring the skirtportion below the bulge.

The apparatus for producing the slits and scores is theoreticallycapable of producing the closures disclosed in U.S. Pat. No. 3,861,551.However, actual practice has shown that the apparatus is noteconomically feasible for being used as production equipment. It hasbeen found that the particular cutting mechanism proposed for producingthe horizontal circumferentially spaced slits produces a tearing actionat opposite ends of the respective slits which may result in sharp edgesbeing developed during the formation of the slits. Also, themulticomponent arrangement for producing the vertical score ispractically impossible to manufacture on a commercial scale because ofthe extremely close tolerances that must be maintained in producing suchapparatus. Furthermore, the multicomponent arrangement requires repeatedrealignment to maintain the required tolerances. It will be appreciatedthat a closure of this type has a wall thickness on the order of 0.010inches and the vertical scores must be accurately controlled to producean acceptable closure that consistently has scores of uniform depth.

Another problem has been observed in using the Hannon type closure.During the rolling operation which attaches the closure to the bottle,it has been observed that the vertical scores are at least partiallysevered adjacent the free edge and the severed edges are overlappedwhich tends to indicate that the closure has been removed at least once.While the obvious solution to such problem would be to increase thethickness of the residual for the score, such solution is not acceptablebecause it would increase the force or turning torque required forremoving the closure.

SUMMARY OF THE INVENTION

According to the present invention, a unique apparatus for forming atamper-proof metal closure of the type disclosed in U.S. Pat. No.3,861,551 is disclosed herein. According to the present invention, acutting and scoring tool is specifically designed to simultaneouslyproduce a plurality of circumferentially spaced slits, interconnected bybridges, and a plurality of vertically extending scores on the lower endof a metal closure. The apparatus is particularly designed for use witha closure forming machine of the type which has a stationary centerportion and a plurality of rotating spindles driven around the peripheryof the center stationary portion.

More specifically, the cutting and scoring tool consists of a firstelongated member that has a free edge which defines a cutting edge andthe cutting edge has a plurality of spaced V-shaped recesses that have adepth which is greater than the thickness of the metal closure. A secondmember is fixed to the first member and has an elongated surface that isspaced from the cutting edges and extends across each of the recesseswith the elongated surface having a plurality of elongated projectionsextending into the respective recesses with free edges thereof spacedfrom the cutting edge so that the metal closure is simultaneously slitand scored in the same operation. This results in being capable ofaccurately positioning the vertical scores with respect to the bridgeportions between the respective horizontally extending slits.

The elongated projections are in the form of V-shaped scoring membersthat have flat peripheral surfaces on the outer edges thereof and arespaced from the cooperating member by a dimension which is less than thethickness of the metal forming the closure.

BRIEF DESCRIPTION OF THE SEVERAL VIEWS OF THE DRAWINGS

FIG. 1 is a schematic illustration of a cap rolling machine having thepresent invention incorporated therein;

FIG. 2 is an enlarged fragmentary sectional view, as viewed along line2--2 of FIG. 1;

FIG. 3 is an enlarged fragmentary plan view of the cutting and scoringtool constructed according to the present invention;

FIG. 4 is a side elevation view of the finished closure;

FIG. 5 is an enlarged fragmentary sectional view, as viewed along line5--5 of FIG. 4;

FIG. 6 is a view similar to FIG. 5 showing a modified form of closure;and

FIG. 7 is a view similar to FIG. 5 showing a further modified form ofclosure.

DETAILED DESCRIPTION

While this invention is susceptible of embodiment in many differentforms, there is shown in the drawings and will herein be described indetail preferred embodiments of the invention with the understandingthat the present disclosure is to be considered as an exemplification ofthe principles of the invention and is not intended to limit theinvention to the embodiments illustrated.

FIG. 1 of the drawings schematically illustrates a cap or closureforming machine, generally designated by the reference numeral 10.Forming machine 10 has a central stationary portion 12 and a circularportion 14 which is rotatable relative to the central portion 12.Rotatable portion 14 has a plurality of spindles 16 supported thereonand spindles 16 are adapted to be rotated about their own axes in thedirection indicated by the arrow 18. The basic machine may be of thetype that is presently available from Aluminum Company of America,Richmond Works, Richmond, Ind., and identified as a PM-17 cap rollingmachine.

According to one aspect of the present invention, cap rolling machine 10incorporates a single station 20 for simultaneously deforming, knurling,slitting and scoring a cap to form a finished closure 22, as illustratedin FIG. 4. Closure 22 has a substantially flat top wall 24 and aperipheral cylindrical skirt 26 extending downwardly from the outerperimeter of the flat top wall 24 with cylindrical skirt 26 terminatingin a lower free edge 27. Skirt or cylindrical side wall 26 has a knurledband 28 defined at the upper end thereof and a flat slightly taperedportion 29 below the knurled band 28 with an inwardly directed bead 30at the upper end of tapered portion 29. Tapered portion 29 is capable ofbeing deformed into a threaded section when bottle closure 22 is finallysecured to the threaded neck of a bottle. An outwardly extending bulge31 is located at the lower end of tapered portion 29 and bulge 31 mayalso be knurled, if desired. A plurality of circumferentially spacedslits 32 are formed in the outwardly extending bulge 31 intermediateupper and lower ends thereof. Slits 32, which extend perpendicular tothe axis of skirt 26, are separated by bridges 33 and define a band 34adjacent free edge 27. Band 34 has a plurality of lines of weakness 35which extend perpendicular to the slits and parallel to the axis ofclosure 22 and the lines of weakness are equal in number to the bridgesand are respectively aligned therewith, as more clearly illustrated inFIG. 4. The closure so far described is of the type illustrated inHannon U.S. Pat. No. 3,861,551, portions of which are consistentherewith being incorporated herein by reference.

As illustrated in FIG. 4 and disclosed in the Hannon patent, there arepreferably eight bridges 33 around the perimeter of disclosure 22.

According to one aspect of the invention, the respective lines ofweakness 38 are formed in a unique fashion to prevent severing of thelines of weakness while the closure is rolled onto the bottle. Morespecifically, each line of weakness has a residual thickness at freeedge 27 which is greater than the residual thickness of the line ofweakness at its opposite end adjacent slits 32.

As illustrated in FIG. 5, each line of weakness 35, includes a firstportion 35a at free edge 27 which has a residual thickness equal to thethickness of side wall 26 and a second portion 35b which has a thicknesssubstantially less than side wall 26. In addition, first portion 35a hasa dimension axially of cylindrical side wall 26 which is greater thanthe thickness of side wall 26. The axial dimension is preferably in therange of about one to about three times the thickness of side wall 26.

While not limited to any specific dimensions, a specific example will bedescribed. A closure 22 formed from aluminum having a side wallthickness of 0.009 inches and the axial dimension of unscored portion35a was 0.015 inches while the residual thickness of scored portion 35bwas 0.002 inches.

It has been determined that leaving an unscored portion at the free edgeof tamper-proof band 34 for each line of weakness 35 allows for greaterlatitude in the residual thickness of scored portion 35b. By properselection of the axial dimension of unscored portion 35a, it is believedthat the residual thickness may be as much as 0.005 inches and theclosure can still be removed by applying a turning torque withinrequired limits for such closures.

In fact, it is possible that scored portion 35b could be in the form ofan axial slot 35c, as illustrated in FIG. 6, to produce each line ofweakness. Alternatively, each line of weakness 35 could have aconstantly reducing residual thickness 36 from free edge 27 to theopposite end thereof, as illustrated in FIG. 7. Of course, the residualthickness of scored portion 35b could also be of varying thickness fromone end to the opposite end thereof.

Actual tests have shown that differentially scoring each line ofweakness or having an unscored portion at the free edge of side wall 26allows the closure to be rolled onto the neck of a bottle without havingthe lines of weakness fracture during such operation.

As indicated above, forming tool 20 incorporates mechanism forsimultaneously deforming closure 22 to the configuration illustrated inFIG. 3 as well as producing the circumferentially spaced horizontallyextending slits 34 connected by bridges 36 and vertical lines ofweakness or scores 38.

For this purpose, tool 20 (FIG. 2) includes a knurling member 40 whichcooperates with a circular inner member 42 rotated with spindle 16adjacent the upper end thereof. Members 40 and 42 cooperate to producethe upper knurled band 28. Tool 20 also has a member 44 located directlybelow knurling member 40 and cooperating with a recess 46 on spindle 16to produce an inwardly directed bead 30 located directly below knurledmember 28. Spindle 16 has a cylindrical portion 50 supported thereonwhich has a slightly tapered outer surface 52 and cooperates with acorresponding tapered surface 54 on a cone forming member 56 that formspart of tool 20. The lower peripheral edge of member 56 has a recessportion 58 which cooperates with a circular disc 60 that has an arcuateperipheral surface 62 to produce the upper edge portion of outwardlydirected bulge or bead 31. The apparatus so far described is identicalto the apparatus incorporated into the existing PM-17 cap rollingmachine discussed above.

According to the present invention, the forming, cutting and scoringtool 20 incorporates mechanism for simultaneously producing thecircumferentially spaced horizontally extending slits as well as thevertically extending scores or lines of weakness 35 and accuratelypositioning the slits and lines of weakness with respect to each other.Tool 70 consists of an upper member 72 having a free edge 74 defining acutting edge for producing slits 32. Cutting edge 74 is defined by anupper surface 76 that extends perpendicular to the axis of spindle 18and a lower inclined flat surface 78 and the surfaces are interconnectedat their outer ends by a small flat portion 80. Surfaces 76 and 78cooperate with each other to define a small acute angle A which ispreferably less than 45 degrees and in the specific illustratedembodiment is 30 degrees. The cutting edge 80 cooperates with a circularblade 82 which has a lower peripheral edge thereof in alignment withflat horizontal surface 76 to sever an intermediate portion of outwardlydirected bulge or bead 31.

According to one aspect of the invention, the cutting edge 74 has aplurality of substantially V-shaped recesses 82 which are specificallyconfigured to produce the interconnecting bridges 33 between respectiveslits 32. As most clearly illustrated in FIG. 4, the recesses 82 haveopposed walls 84 that define an angle of substantially less than 90degrees and in the specific embodiment illustrated, this angle is shownas being approximately 45 degrees. As schematically illustrated in FIG.1, eight such recesses are produced at spaced locations along cuttingedge 74 so that the finished closure will have eight slits 32 around thecircumference of bead 31 with eight interconnecting bridges 33 all ofexactly equal length. The advantage of forming the recesses 82 V-shapedin cross-section is that it has been determined that the V-shaped recesseliminates any tearing action at opposite ends of the respective slits.

Tool 70 also includes a second member 90 and second member 90 has anelongated peripheral surface 92 which is spaced from cutting edge 74 andextends across each of the recesses 82. Elongated surface 92 has aplurality of projections 94 extending therefrom and respectively locatedin each of the recesses 82 and being equally spaced from opposed walls84 thereof. Each projection 94 extends parallel to the axis for spindle18 and perpendicular to the cutting edge 74 of member 72 and has a freeedge thereof spaced from cutting edge 74. More specifically, eachelongated projection 94 is substantially V-shaped in cross-section andhas opposed tapered walls 96 that define an angle of substantially lessthan 90 degrees and in the illustrated embodiment, the angle has beenshown as being 60 degrees. The outer peripheral edge of each V-shapedprojection 94 has a flat portion 98. Flat portion 80 on member 72 andflat portion 98 on member 90 preferably have a width of approximately0.002 inches to thereby increase the service life of the cutting andscoring edges.

Members 72 and 90 cooperate with a specifically configured circularmember 100 that is fixed on spindle 16 and has a circular or cylindricalouter surface 102 which has an arcuate bead 104 extending therefrom.Outwardly extending bead 104 is vertically aligned with a recess 106defined between cutting member 72 and scoring member 90 to produce thelower edge portion of outwardly directed bulge 32.

The advantage of using a solid circular member 100 fixed to spindle 16is that the spacing between the free edges 98 of each V-shaped scoringmembers 94 can be accurately controlled to thereby produce a scorehaving a predetermined depth which is uniform for all closures.

As illustrated in FIG. 2, the lower end of each projection is locatedabove lower edge or end 27 of side wall 26 to leave an unscored portion35a for each line of weakness 35. Also, if the residual of portion 35bis designed to be of constantly reducing thickness free edge 98 would beinclined with respect to the cylindrical peripheral surface of member100 and if the line of weakness is to have the configuration illustratedin FIG. 7, the lower end of free edge would be aligned with or below thelower end of side wall 26.

In operation, substantially cylindrical caps having a flat upper walland a cylindrical skirt, which have a diameter substantialy greater thanthe diameter of the respective members rotated with spindle 16, arerespectively inserted upon the upper ends of spindles 16 and thespindles are moved along a circular path identified by the arrow 110 inFIG. 1. Simutaneously, the spindles are rotated about their own axes inthe direction indicated by the arrow 18 in FIG. 1. Preferably, the speedof rotation of spindles 16 is coordinated so that the peripheralsurfaces of the respective caps roll across the forming edges of tool20. Thus, the blank cap is simultaneously deformed, slit and scored andall of the scores or slots and slits are accurately positioned withrespect to each other to insure uniformity for each of the finishedclosures 22.

As can be appreciated from the above description, the present inventionprovides an extremely simple arrangement for producing horizontal slitsand vertical lines of weakness adjacent the lower end of a closure andthe lines of weakness are accurately angularly oriented with respect tothe slits. The utilization of two integral members which respectivelydefine all of the cutting edges and the scoring edges substantiallyreduces the cost of tooling and allows for accurate positioning andalignment of the respective members with respect to each other and withrespect to a spindle cooperating therewith.

I claim:
 1. Apparatus for forming a tamper-proof metal closure having aplurality of circumferentially spaced slits separated by bridges and aplurality of lines of weakness extending perpendicular to said slits andaligned with respective bridges, comprising at least one mandrel forreceiving a cup-like member, means for rotating said mandrel about itsaxis and simultaneously moving said mandrel along a path, and astationary tool located adjacent said path, the improvement of said toolincluding a first integral elongated member having a free edge defininga cutting edge for producing said slits, said cutting edge having aplurality of spaced V-shaped recesses having a depth greater than thethickness of the metal closure, a second member fixed to said firstmember, said second member having an elongated surface generallyparallel to and spaced from said cutting edge and extending across anintermediate portion of each of said recesses, said elongated surfacehaving a plurality of elongated projections extending therefrom andforming an integral part thereof, each projection being located in arespective recess, each elongated projection extending substantiallyperpendicular to and having a free edge spaced from said cutting edge,and cooperating means on said mandrel cooperating with said members forsimultaneously producing said slits and lines of weakness.
 2. Apparatusas defined in claim 1, in which said path is circular and said first andsecond members are arcuate and located inside said circular path. 3.Apparatus as defined in claim 2, in which there are a plurality ofmandrels spaced along said path.
 4. Apparatus as defined in claim 1, inwhich said V-shaped recesses each have opposed walls defining an anglesubstantially less than 90 degrees.
 5. Apparatus as defined in claim 1,in which each projection is substantially V-shaped in cross-section andhas opposed tapered flat walls defining an angle substantially less than90 degrees.
 6. Apparatus as defined in claim 1, in which said firstmember has a flat surface extending perpendicular to the axis of saidmandrel and an inclined surface cooperating with said flat surface toproduce said cutting edge and in which the included angle of saidcutting edge surfaces is less than 45 degrees.
 7. Apparatus as definedin claim 1, in which said cooperating means include a fixed memberhaving a cylindrical peripheral surface with an outwardly directedintegral bead at an upper end of said peripheral surface and a free endof said cup-like member is on said peripheral surface.
 8. Apparatus asdefined in claim 7, in which each free edge of each projection isinclined with respect to said cylindrical peripheral surface so thateach line of weakness has a varying residual thickness.
 9. Apparatus asdefined in claim 7, in which a lower edge of each projection is spacedabove said free end of said cup-like member to leave an unscored portionat said free end of each cup-like member.